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How Life Arose on Earth, and How a Singularity Might Bring It Down

The views expressed are those of the author and are not necessarily those of Scientific American.


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It didn’t take long for the recent Foundational Questions Institute conference on the nature of time to delve into the purpose of life. “The purpose of life,” meeting co-organizer and Caltech cosmologist Sean Carroll said in his opening remarks, “is to hydrogenate carbon dioxide.” Well, there you have it. Carroll is one of the most reflective scientists I know and would never claim to reduce all of human existence to molecular disequilibrium. Still, it’s nice to know your place in the grand scheme of things. The FQXi meeting had much to say about where we came from—and where we’re headed.

Last year, Carroll blogged the backstory of where his purpose-of-life line came from. He had bumped into Mike Russell of JPL, an expert on the origin of life, on an airplane and got to chatting about the role that living things play in the geochemical cycles of our planet. Russell was on hand at the FQXi conference, too, and elaborated on his engrossing thesis tracing our descent to inorganic chemical reactions.

In Russell’s picture, the primeval Earth looked uncannily like a giant bacterium. At the seafloor, in spots like the Lost City hydrothermal vents, the chemically reduced interior met the oxidized exterior, creating a state of chemical disequilibrium. Hydrogen bubbling up from the interior sought to combine with carbon dioxide dissolved from the atmosphere to form methane, but this reaction has a bottleneck because intermediate stages such as formaldehyde require an input of energy (see this helpful graph). A geochemical reaction known as serpentinization can push through the bottleneck, using metals such as iron as catalysts, but biological reactions are more efficient, and Russell mapped out a series of steps whereby serpentinization would evolve into membrane-encased cells.

Evolution at this stage was not by natural selection, but by the spontaneous generation of complexity; the Darwinian version came later as information-bearing molecules arose. The scenario is commonly referred to as “metabolism-first” as opposed to “genetics-first.” It is the protobiological version of the principle that the way to a man’s heart is through his stomach.

The process would have given birth to two of the three kingdoms of life, bacteria and archaea. Russell suggested that life might have arisen multiple times on Earth and, indeed, on any planet with similar chemical imbalances. Phylogeny replicates geology.

We also heard from two researchers who have looked at Darwinian evolution in action. Michael Lässig of the University of Köln has studied seasonal flu patterns for clues to how evolution operates. The flu makes me wish intelligent design were true. We might have some hope of outwitting a designer, rather than remain locked in perpetual combat with a shape-shifting adversary. The influenza virus is continually improving its fitness. Lässig has found that, contrary to expectations, mutations that benefit the virus are actually quite common. If it is any consolation, the virus faces a Sisyphean task. Though continually improving, its fitness never actually gets any higher, because the very definition of fitness keeps changing under pressure from our own immune systems.

Richard Lenski of Michigan State described his fascinating experiments on the evolution of E. coli. In 1988 he started to culture 12 populations of the bug and, since then, has seen 53,000 generations come and go—far more than the total number of human generations that has ever lived. Every 500, he freezes a sample of each population as a snapshot of evolutionary history.

Lenski and his team find that the bacterium, like the flu virus, perpetually increases its fitness—meaning, in this case, its proficiency at consuming glucose and reproducing. As good as the organisms are at those two tasks, they can always get even better—the scope for improvement is essentially infinite. And as with flu, most of the genetic changes in E. coli occur by natural selection than by random genetic drift. A population of a given generation is more similar to the other independent populations than to its own ancestors.

The coolest thing is that, while most of the lineages contented themselves with glucose, one eventually wised up to the fact that their petri dishes contained citrate, too, and developed a taste for it. When the researchers noticed this, they went into the freezer, pulled out earlier generations of that strain, and recultured them—replaying evolution to study how exactly the bacterium learned to broaden its diet. Lenski showed pictures of the giant stacks of petri dishes it took to watch history unfold again. Sympathetic murmurs of pity for the grad students spread through the FQXi audience.

The team found that nearly two dozen strains also managed to discover the citrate. Their newfound talent involved a complex rearrangement of bacterial DNA that did not come about in one mutation, but from a series of mutations. Early mutations having nothing to do with citrate were required to set the stage for the eventual citrate epiphany. To paraphrase John Lennon, evolutionary breakthroughs are what happens when you’re making other plans.

Lenski’s work demonstrates that evolution is broadly repeatable. Geoffrey West of the Santa Fe Institute made much the same point when he showed the scaling relations that all living things follow. His and his colleagues’ work has gotten a lot of attention in recent years, but this was the first time I’d seen him speak, and if I’d been a student, his talk might well have caused me to change majors.

It’s incredible, really, how such vastly different systems follow the same simple relations of size and energetics, reflecting economies of scale that all complex structures are subject to. West and Luís Bettencourt have an article in our September issue on the scaling relations that describe cities, which look uncannily like those that govern organisms. Here are three of my favorites:

  • An organism’s lifespan is proportional to the 1/4 power of its mass, its heart rate goes as the –1/4 power of its mass, so the total number of heart beats is independent of mass—a universal value of about a billion beats for all of us. Use them wisely.
  • The metabolic rate goes as the 3/4 power of body mass—in three spatial dimensions. More generally, it goes as the D/(D+1) power. I take this as meaning that higher-dimensional organisms achieve fewer economies of scale.
  • People really do walk faster in cities—the walking speed scales with city size.

In fact, the patterns were so impressive that they started to bring out my contrarian side. If I were a student, I’d probably start by seeing how universal they really are and what deviations represent.

Toward the end of this talk, West went way beyond the Sci Am article and got into the implications for the near-future of humanity, which he also talked about in an Edge interview this spring. West said he sees a recurring historical pattern: the pace of life accelerates, reaches a breaking point, and precipitates a major transition—a “singularity”—in which new technology or ways of doing things offer some respite. It doesn’t last long before things pick up again, faster than ever. Over time, the acceleration accelerates. Transitions come faster and furiouser. Sustainability is elusive. We’re basically all screwed.

The alternative—that the superexponential growth finally levels off for good—is fraught with dangers, too. Complexity theorist Raissa D’Souza of U.C. Davis argued in her talk that when you have coupled complex systems, any break in the growth trends tends to be accompanied by wild fluctuations. Modern society is predicated on growth; stability is tantamount to collapse.

I’ve never really bought into the Singularity worries—I tend to think they overextrapolate a very narrow kind of high-tech progress. The things that dictate our quality of life are mainly low-tech: soft beds, flush toilets, smooth roads, fresh veggies. A single supermarket trip costs you more than an iPhone. But West did make a worrisome case that the accelerating pace of change goes way beyond Moore’s law and pervades every corner of our lives.

Of all the talks at the conference, West’s talk was the one that touched on what, for most people, is the biggest mystery of time: that there never seems to be enough of it. If you think that’s true now, just wait. I keep hoping there’ll be a collective exhalation, things will calm down, my email box won’t fill up faster than I can empty it. We need the 21st-century version of “turn on, tune in, drop out.” The conference itself offered a solution to that: for much of the time, we had awful Internet access. It was amazing how being unplugged opened up the day. We spent hours talking about the deepest questions of science and never felt rushed. I can’t wait to do it again.

Photo of Lost City hydrothermal field, courtesy of NOAA. Photo of petri dishes, courtesy of Richard Lenski’s laboratory.

George Musser About the Author: is a contributing editor at Scientific American. He focuses on space science and fundamental physics, ranging from particles to planets to parallel universes. He is the author of The Complete Idiot's Guide to String Theory. Musser has won numerous awards in his career, including the 2011 American Institute of Physics's Science Writing Award. Follow on Twitter @gmusser.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Nimbusian 2:43 pm 09/24/2011

    Very interesting article. The other day watched a TED presentation by West, goes along fairly well with the article (esp his description of scaling).

    http://www.ted.com/talks/geoffrey_west_the_surprising_math_of_cities_and_corporations.html

    Link to this
  2. 2. Jennifer Ouellette 3:37 pm 09/24/2011

    George, your coverage of the conference has been so good, I sadly feel no need to blog about it myself. :) Keep ‘em coming!

    Link to this
  3. 3. Shoshin 6:07 pm 09/24/2011

    The ultimate purpose of all life is to increase entropy. Life is favored as a chemical process which speeds and catalyzes this universal law.

    Intelligence is further favored as it can increase entropy far out of proportion to the needs of its brain’s biological carrying case.

    If people didn’t exist, the laws of thermodynamics would have invented us anyway.

    Link to this
  4. 4. jhewitt 10:33 pm 09/25/2011

    Great article. Taking an average of 60-100 beats/minute for adult humans, a billion beats in a lifetime gives us an expected life span of between 19 and 31.7 years. The higher end of this range is close to some paleodemographic estimates of early human lifespans, but factors such as evolving behavioral repertoires and technologies have moved us well beyond the “universal value”.

    Link to this
  5. 5. radobozov 8:05 am 09/26/2011

    Shoshin,

    “The ultimate purpose of all life is to increase entropy. Life is favored as a chemical process which speeds and catalyzes this universal law.”

    Wrong – the ultimate purpose of life is to store energy in form of living interfering systems governed by the origin of carbon interference.

    Link to this
  6. 6. radobozov 8:11 am 09/26/2011

    To the author:
    “The metabolic rate goes as the 3/4 power of body mass—in three spatial dimensions. More generally, it goes as the D/(D+1) power. I take this as meaning that higher-dimensional organisms achieve fewer economies of scale.”

    What is 1 in the sense of energy? What is a dimension – a measurable fundamental constant?
    Space is matter occupying time determined by the interference of particles/strings/waves. What about antimatter?

    Link to this
  7. 7. jtdwyer 8:34 am 09/26/2011

    Any purpose assigned to life that does not directly benefit life attributes its existence to some external source. Hydrogenate carbon-dioxide? Wasn’t that the purpose we assigned to ancient flora? Who are we supposedly fulfilling this purpose for?

    The purpose of life is to sustain and reproduce life. Contrary to all indications of humanity’s success, we are now jeopardizing that purpose.

    Link to this
  8. 8. oldvic 11:36 am 09/26/2011

    I see a way out of the current rat race: a change from a society that works towards quantitative growth to another that aims at qualitative growth.

    I don’t see that we have much choice. We live inside a limited system and we’ll have to reach a quantitative plateau sooner or later, unless we learn to fly through space and become proficient in adapting to new planets (and even that would be a temporary solution).

    Anyway, if I’m wrong, you’ll all get your money back.

    Link to this
  9. 9. ParrotSlave 1:50 pm 09/26/2011

    So “People really do walk faster in cities—the walking speed scales with city size.” Maybe walking speed correlates with the fear of getting robbed, which, I suspect, scales with city size also.

    Link to this
  10. 10. Kurt L Hanson 8:44 pm 09/26/2011

    Attempting to distinguish the forest from the trees, the question is or should be, ‘Where did the force/energy of the Big Bang originate from?’ Since it could not have originated from some type of thing which does not exist, it must have originated from some type of thing already existent. Furthering the thought, quantum theory doesn’t prove the existence of other universes. There is and can be proven that only this one universe we are inside of is known to exist. The hypothetical is then, ‘What system or method is directing the initial, chaotic force/energy of the Big Bang to cause molecules of DNA and thus biological life to exist inside this’ee here universe.’

    Excuse me. I’m simply attempting to see the forest from the trees.

    Link to this
  11. 11. Qedlin 12:24 am 09/27/2011

    Amazing, expecting to receive some new insight from the majisterium of science and all we get is “hydrogenated CO2?” Another demonstration of science’s disqualification to venture outside the strict bounds of defined science.

    And for a grand conclusion, “we are all screwed.” QED.

    Nothing of substance justifying the title – merely more arm-waiving stamp collectors and taxidermists straining to keep the cult of Chuckie alive and demonstrating the human aphorism that compels us to trivialize what we do not understand, viz., life, existence and purpose.

    Link to this
  12. 12. solum23 5:27 am 09/27/2011

    as a human being,we are the students of this world.for a admission in 10th std.,you have to clear 9th class.so, this world is a sort of 9th std.

    Link to this
  13. 13. ptschneider 4:54 pm 09/28/2011

    Sean Carroll is being very myopic.
    The purpose of life is the replication of ribonucleic acids and their associated proteins.
    The hydrogenation of carbon dioxide is just a side-effect.

    Link to this
  14. 14. P.A. Wahid 11:17 pm 01/19/2012

    Although biology is the science of life, biologists do not know what life is; geneticists do not know what the gene is; and evolutionists do not know what species is! This is the plight of biology now. Biology literature continues to grow at an alarming rate in these fields! Scientists never stop to think whether science is advancing in the right direction. It is without knowing what life is, biologists are trying to create it. The basic reason why we cannot define or understand the phenomenon of life is the molecular gene (genome) concept is wrong. Biological program responsible for the functioning of an organism is not encoded by a chemical molecule (DNA). By treating DNA as the molecule of life, we are superimposing biological information over chemical information. DNA is the only molecule in the whole universe that carries biological information over and above chemical information! The molecular gene concept is scientifically untenable. It is violation of chemical principles. The Quran reveals that life is non-material phenomenon validating the original proposal of nonphysical gene by Wilhelm Johannsen in 1909. He warned against two things while proposing the gene concept; one is against treating gene as material entity, and the other is against assigning gene for particular character. Both his warnings have been now proved correct.
    The nonphysical biological information can be conceived on the lines of computer concept of the organism. Phenomena of life and death can be defined and explained in the light of the Quranic revelation based on the computer model of organism. The Quran informs that nonphysical rooh (or nafs) (“breath of life” in the Bible) is the cause of life and its removal (deletion) from the body results in death. In the computer model, the chemical structures (including DNA) from cells through tissues to organs constitute hardware of the organism. The nonphysical rooh is the biosoftware of organism. The computer software is also nonphysical although it requires a physical medium (disk) for storage. Similarly biosoftware also requires a physical medium for its storage. The hard disk of organism is chromosome. The invisible software is the soul of the computer as the rooh is the soul of an organism. As the deletion of rooh causes death, deletion of the software also brings the computer to a halt. A dead body is like a computer without software. Based on this reasoning, life can be defined as the manifestation of execution of divine biosoftware in body, and death as the result of its deletion from the body. This assertion based on the Quran is falsifiable. It predicts it will be impossible to create life from non-life without using a living cell or organism at any stage of the process. It also predicts that a dead cell (or dead body) cannot be restored to life. In fact a dead cell has all the material structures including DNA intact at death. But yet the cell doesn’t show any sign of life. This shows a chemical structure (material) does not constitute biological program. All the experiments to create life from non-life going on at various centres in the world are destined to fail proving that molecular gene concept is the costliest blunder ever to commit in the history of science. It will also prove God. Biologists can as well test their idea of material gene by bringing a dead cell back to life by chemical means since dead cell is comparable to prosthetic cell. They don’t have to create genome or cell from scratch chemically, which is not feasible without involving living cell or organism. Our computer, robots, etc., which run on man-made software are forms of ‘artificial life’. For detailed discussion please see posts 4 and 5 at my blog http://quranscienceblog.blogpost.com
    Creating changes in organism through genetic manipulation is not creation of life. Nature herself shows such diversity within species. In computer model of organism, DNA technology is biohardware technology and not biosoftware technology. By that scientists are trying to find hardware solution for software problem.

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  15. 15. Kurt L Hanson 3:19 am 07/26/2012

    Mohamed proclaimed, “I was ordered to fight all men until they say there is no god but Allah” (cf. Sahih Bukhari), thereby establishing violent jihad as the immutable, eternal core of Islam.

    Peace is the doctrinal basis and main practical principle of Christianity. Jesus implored us to “turn the other cheek” and “let he who has not sinned cast the first stone.”  Those who waged violence in the name of expanding the realm of Christianity (rather than in its defense) did so in violation of its dictates. 
    Alternately, Mohamed proclaimed, “I was ordered to fight all men until they say there is no god but Allah” (cf. Sahih Bukhari), thereby establishing violent jihad as the immutable, eternal core of Islam.
    In accordance with Shari’a, Mohamed’s above proclamation is eternal.  Islam may never reform and attempts to reinterpret this doctrine are considered takfir (essentially heresy).  Unless practicing taqiyya or kitman (sanctioned deception) in Islamically valid efforts to deceive the kuffar, any Muslim who genuinely embraces a contrary principle will be considered an apostate and subject to a capital fatwa from any cleric of the four Madh’hab schools of Islamic jurisprudence (as well as the Shia fiqhs).
    Thus, there is no growth cycle.  By Islamic law, Islam is locked in 14th century jurisprudence.  But don’t take MY word for it, find out for yourself:  get the Muslim compendium “Reliance on the Traveller;” it is the 14th century Islamic source document relied on for the past 600 years by the Muslims themselves, and contains the core legal principles of conduct under the Islamic system.

    Link to this

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